Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> P;

int h,w;
int fie[51][51];
int dist[51][51];
int dx[4]={0,1,0,-1};
int dy[4]={1,0,-1,0};

int main(void){
	scanf("%d%d",&h,&w);
	int cnt=0;
	for(int i=0;i<h;i++){
		string str;
		cin >> str;
		for(int j=0;j<w;j++){
			if(str[j]=='#'){
				fie[i][j]=-1;
				cnt++;
			}
		}
	}
	memset(dist,-1,sizeof(dist));
	dist[0][0]=0;
	queue<P> que;
	que.push(P(0,0));
	while(que.size()){
		P p=que.front();
		que.pop();
		for(int i=0;i<4;i++){
			int nx=p.second+dx[i];
			int ny=p.first+dy[i];
			if(nx>=0 && ny>=0 && nx<w && ny<h){
				if(dist[ny][nx]==-1 && fie[ny][nx]==0){
					dist[ny][nx]=dist[p.first][p.second]+1;
					que.push(P(ny,nx));
				}
			}
		}
	}
	if(dist[h-1][w-1]==-1){
		puts("-1");
	}else{
		printf("%d\n",h*w-cnt-dist[h-1][w-1]-1);
	}
	return 0;
}